KIEV, Ukraine — Ukraine's president pleaded with the United Nations on Monday to send peacekeeping troops to eastern Ukraine to expel separatist militants from government buildings — a takeover he said is being directed by Russian special operations troops.

Acting President Oleksandr Turchynov asked in a telephone call to U.N. Secretary-General Ban Ki Moon that an "anti-terrorist operation" could be conducted jointly by Ukrainian security forces and U.N. peacekeepers to end the crisis. But Russia holds a veto on the Security Council, so it is unlikely the U.N. would approve such a force.

Meanwhile, separatists continued to hold government buildings in 10 cities in eastern Ukraine and refused to abide by a Monday morning deadline set by the Kiev government for them to vacate. Russia said it was watching events and reserved the right to intervene. Britain said Russia already has.

The coordinated action of the armed pro-Russian groups inside Ukraine "is something that is being planned and brought about by Russia," British Foreign Secretary William Hague said ahead of a meeting with his EU counterparts.

Numerous media outlets and the Ukrainian government have reported groups of well-armed masked men in matching uniforms without insignias directing the setting up of barricades outside occupied government buildings. Russia also has moved 40,000 troops and tank columns to its border with eastern Ukraine.

"I'll be arguing today that sanctions, further sanctions, have to be the response to Russia's behavior," Hague said.

The United States and Europe have already imposed economic sanctions on a handful of Russian businessmen and officials following Moscow's takeover militarily of the Ukrainian province of Crimea.

European Union foreign ministers plan to meet in Geneva on Thursday to discuss ways to defuse tensions. Diplomats from the United States, Russia, the EU, Ukraine and Switzerland were expected at the talks.

"We are actively evaluating what is happening in eastern Ukraine, what actions Russia has taken, what transgressions they've engaged in," White House spokesman Jay Carney said. "And we are working with our partners and assessing for ourselves what response we may choose."

The European Union told the Associated Press that foreign ministers have decided to sanction more Russians with asset freezes and visa bans as a sign of opposition to Moscow's policy toward Ukraine. Critics of the West's response say it must be stronger on Russian President Vladimir Putin.

"Certainly the preconditions are being put in place" to invade as Russia did in Crimea, said John Bolton, who was U.S. ambassador to the United Nations under President George W. Bush.

Bolton told Fox News that sanctions imposed by the White House thus far are "pinpricks" that will not deter Putin. He suggested far stronger sanctions, such as denying Russian businesses and financial institutions access to Western financial markets, "to make therm feel pain."

"Putin thinks he is on a roll. He sees Europe and the United States not responding," Bolton said.

Such action would require the approval of all 28 members of the European Union. Frans Timmermans, the Dutch foreign minister, said it was too early to impose more sanctions. The White House also blamed Putin for fanning flames of unrest in Ukraine but has not announced any new measures against Russia.

Dmitry Peskov, spokesman for Putin, was quoted by Russian news agencies as saying Monday that Putin has received "numerous appeals" from eastern Ukraine "asking him to help and interfere in one way or another." Peskov added that Putin was "watching the developments in those regions with great concern" but wouldn't elaborate.

The Ukrainian government took no immediate action following the lapsed deadline and further takeover of buildings.

Ukrainian Deputy Foreign Affairs Minister Danylo Lubkisvskiy said Monday that Ukraine's government hopes the meeting in Geneva may achieve results.

"Russia is alarmed about the meeting in Geneva," said Lubkivskiy, who said if Russia continues to provoke the situation in the east, Ukraine will close the border with its neighbor.

Russia has warned the Kiev government not to use force against the armed protesters in the east. Russian Foreign Minister Sergey Lavrov denied Monday that Russian agents were operating in eastern Ukraine, saying it would contradict Moscow's interests.

In Horlivka, however, the Associated Press reported that one of the men directing the raid on the police headquarters introduced himself as a lieutenant colonel in the Russian army to a line of policemen who had switched sides.

Horlivka, which has a population of 258,000 people, is located close to the region's capital, Donetsk, where separatist's have been in control of a state administration building since April 6.

The protests in the east turned deadly Sunday when at least two people were killed in Sloviansk, a State Security Service officer and one civilian. Ukrainian news services reported that four people were killed, citing their own sources.

Former prime minister Yulia Tymoshenko, recently released from jail after Kiev ousted pro-Mosocw president Viktor Yanukovych, also urged the international community to intervene in the country.

"I ask leaders of the world to provide direct military help to the Ukrainian people who have been fighting for their freedom and die for it. I ask the leaders to act," she said.

Ukrainians in Donetsk expressed disappointment with Kiev's slow reaction to the unrest in the region.

"I thought Donetsk has proved with its mass rallies that it's truly is a Ukrainian city, but Kiev either doesn't believe that there are more pro-Ukrainian people here than separatists, or Kiev just betrayed us," Anastasia Balabanova said.

She doesn't have much confidence in the West either.

"No-one will fight for us at the cost of ruining relations with Russia," Balabanova said.

The separatists have demanded a referendum to secede from Ukraine and join Russia, similar to one held in Crimea in which nearly all those who voted were allegedly in favor of joining Russia.

The West says the Crimean vote was rigged and illegal. Polls indicate that most of eastern Ukraine would like more autonomy from the capital of Kiev but do not want to join Russia.

The International Republican Institute, a non-profit polling group, conducted a survey of Ukrainians from all backgrounds and regions — including Crimea — and backgrounds and found that 81% opposed joining Russia. Only 13% were in favor.

Putin has justified his intervention in Ukraine by saying the lives of ethnic Russians are in danger from Ukraine's government, but the poll conducted March 14-26 by Gallup and IRI found that 85% of Ukrainians say Russian-speaking citizens are not threatened. Even 66% of ethnic Russians agreed.

The survey of 1,200 Ukrainians were based on interviews conducted in person at respondents' homes.

"These findings contradict claims by Moscow that Russian-speaking citizens are being threatened, a claim many believe is a pretext to further Russian incursions into Ukraine," stated IRI.

However, Turchynov said Monday that holding a nationwide referendum on the nation's status was a possibility, the Russian Interfax news agency reported. At the same time, Serhiy Taruta, governor of the Donetsk region where government buildings were seized in several cities, said an anti-terrorist operation was underway.

Taruta said the anti-terrorism measures were aimed at "protecting the peace and order on our land, which today is being taken away from us by armed, aggressive fanatics cynically and cold-bloodedly," he was quoted by Interfax as saying. "They are terrorists and we will not let them rule on our land." He did not provide any details of the operation.